On z/VM, using PER, you can see that MVCL is interruptible: issuing one for a big area (typically MB), you may see the same instruction traced multiple times. Kinda fun. At least that was true at some point; been a while since I've used PER in anger.
-----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Attila Fogarasi Sent: Friday, July 26, 2024 5:56 PM To: [email protected] Subject: Re: Does MVCDK move 'per byte' like MVC? To answer "how can you tell", another TCB will see a partial move for MVCL while only the complete move is seen for MVC. Rather important for some multi-tasking code. On some older machines such as CMOS the partial move was on a cache line boundary, so by block but not predictable. Don't know for current hardware, where cache management is much more sophisticated. Made for some interesting bugs for pre-z. On Sat, Jul 27, 2024 at 7:35 AM Paul Gilmartin < [email protected]> wrote: > On Fri, 26 Jul 2024 16:03:40 -0500, Mike Schwab wrote: > > >MVC has another exemption. The entire 256 bytes appear to move at > >once. > > > How can you tell? How might this "appear" different from moving > sequentially? Was that true even on the earliest s/360? Is that to > say that the move appears "block concurrent"? > > > ... Vs MVCL appears to move 1 byte at a time with register updates. > > -- > gil > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send > email to [email protected] with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
